fs/fuse/fuse_i.h

   1 /*
   2   FUSE: Filesystem in Userspace
   3   Copyright (C) 2001-2008  Miklos Szeredi <miklos@szeredi.hu>
   4
   5   This program can be distributed under the terms of the GNU GPL.
   6   See the file COPYING.
   7 */
   8
   9 #ifndef _FS_FUSE_I_H
  10 #define _FS_FUSE_I_H
  11
  12 #ifndef pr_fmt
  13 # define pr_fmt(fmt) "fuse: " fmt
  14 #endif
  15
  16 #include <linux/fuse.h>
  17 #include <linux/fs.h>
  18 #include <linux/mount.h>
  19 #include <linux/wait.h>
  20 #include <linux/list.h>
  21 #include <linux/spinlock.h>
  22 #include <linux/mm.h>
  23 #include <linux/backing-dev.h>
  24 #include <linux/mutex.h>
  25 #include <linux/rwsem.h>
  26 #include <linux/rbtree.h>
  27 #include <linux/poll.h>
  28 #include <linux/workqueue.h>
  29 #include <linux/kref.h>
  30 #include <linux/xattr.h>
  31 #include <linux/pid_namespace.h>
  32 #include <linux/refcount.h>
  33 #include <linux/user_namespace.h>
  34
  35 /** Default max number of pages that can be used in a single read request */
  36 #define FUSE_DEFAULT_MAX_PAGES_PER_REQ 32
  37
  38 /** Bias for fi->writectr, meaning new writepages must not be sent */
  39 #define FUSE_NOWRITE INT_MIN
  40
  41 /** It could be as large as PATH_MAX, but would that have any uses? */
  42 #define FUSE_NAME_MAX 1024
  43
  44 /** Number of dentries for each connection in the control filesystem */
  45 #define FUSE_CTL_NUM_DENTRIES 5
  46
  47 /** Maximum of max_pages received in init_out */
  48 extern unsigned int fuse_max_pages_limit;
  49
  50 /** List of active connections */
  51 extern struct list_head fuse_conn_list;
  52
  53 /** Global mutex protecting fuse_conn_list and the control filesystem */
  54 extern struct mutex fuse_mutex;
  55
  56 /** Module parameters */
  57 extern unsigned max_user_bgreq;
  58 extern unsigned max_user_congthresh;
  59
  60 /* One forget request */
  61 struct fuse_forget_link {
  62         struct fuse_forget_one forget_one;
  63         struct fuse_forget_link *next;
  64 };
  65
  66 /* Submount lookup tracking */
  67 struct fuse_submount_lookup {
  68         /** Refcount */
  69         refcount_t count;
  70
  71         /** Unique ID, which identifies the inode between userspace
  72          * and kernel */
  73         u64 nodeid;
  74
  75         /** The request used for sending the FORGET message */
  76         struct fuse_forget_link *forget;
  77 };
  78
  79 /** Container for data related to mapping to backing file */
  80 struct fuse_backing {
  81         struct file *file;
  82         struct cred *cred;
  83
  84         /** refcount */
  85         refcount_t count;
  86         struct rcu_head rcu;
  87 };
  88
  89 /** FUSE inode */
  90 struct fuse_inode {
  91         /** Inode data */
  92         struct inode inode;
  93
  94         /** Unique ID, which identifies the inode between userspace
  95          * and kernel */
  96         u64 nodeid;
  97
  98         /** Number of lookups on this inode */
  99         u64 nlookup;
 100
 101         /** The request used for sending the FORGET message */
 102         struct fuse_forget_link *forget;
 103
 104         /** Time in jiffies until the file attributes are valid */
 105         u64 i_time;
 106
 107         /* Which attributes are invalid */
 108         u32 inval_mask;
 109
 110         /** The sticky bit in inode->i_mode may have been removed, so
 111             preserve the original mode */
 112         umode_t orig_i_mode;
 113
 114         /* Cache birthtime */
 115         struct timespec64 i_btime;
 116
 117         /** 64 bit inode number */
 118         u64 orig_ino;
 119
 120         /** Version of last attribute change */
 121         u64 attr_version;
 122
 123         union {
 124                 /* read/write io cache (regular file only) */
 125                 struct {
 126                         /* Files usable in writepage.  Protected by fi->lock */
 127                         struct list_head write_files;
 128
 129                         /* Writepages pending on truncate or fsync */
 130                         struct list_head queued_writes;
 131
 132                         /* Number of sent writes, a negative bias
 133                          * (FUSE_NOWRITE) means more writes are blocked */
 134                         int writectr;
 135
 136                         /** Number of files/maps using page cache */
 137                         int iocachectr;
 138
 139                         /* Waitq for writepage completion */
 140                         wait_queue_head_t page_waitq;
 141
 142                         /* waitq for direct-io completion */
 143                         wait_queue_head_t direct_io_waitq;
 144
 145                         /* List of writepage requestst (pending or sent) */
 146                         struct rb_root writepages;
 147                 };
 148
 149                 /* readdir cache (directory only) */
 150                 struct {
 151                         /* true if fully cached */
 152                         bool cached;
 153
 154                         /* size of cache */
 155                         loff_t size;
 156
 157                         /* position at end of cache (position of next entry) */
 158                         loff_t pos;
 159
 160                         /* version of the cache */
 161                         u64 version;
 162
 163                         /* modification time of directory when cache was
 164                          * started */
 165                         struct timespec64 mtime;
 166
 167                         /* iversion of directory when cache was started */
 168                         u64 iversion;
 169
 170                         /* protects above fields */
 171                         spinlock_t lock;
 172                 } rdc;
 173         };
 174
 175         /** Miscellaneous bits describing inode state */
 176         unsigned long state;
 177
 178         /** Lock for serializing lookup and readdir for back compatibility*/
 179         struct mutex mutex;
 180
 181         /** Lock to protect write related fields */
 182         spinlock_t lock;
 183
 184 #ifdef CONFIG_FUSE_DAX
 185         /*
 186          * Dax specific inode data
 187          */
 188         struct fuse_inode_dax *dax;
 189 #endif
 190         /** Submount specific lookup tracking */
 191         struct fuse_submount_lookup *submount_lookup;
 192 #ifdef CONFIG_FUSE_PASSTHROUGH
 193         /** Reference to backing file in passthrough mode */
 194         struct fuse_backing *fb;
 195 #endif
 196 };
 197
 198 /** FUSE inode state bits */
 199 enum {
 200         /** Advise readdirplus  */
 201         FUSE_I_ADVISE_RDPLUS,
 202         /** Initialized with readdirplus */
 203         FUSE_I_INIT_RDPLUS,
 204         /** An operation changing file size is in progress  */
 205         FUSE_I_SIZE_UNSTABLE,
 206         /* Bad inode */
 207         FUSE_I_BAD,
 208         /* Has btime */
 209         FUSE_I_BTIME,
 210         /* Wants or already has page cache IO */
 211         FUSE_I_CACHE_IO_MODE,
 212 };
 213
 214 struct fuse_conn;
 215 struct fuse_mount;
 216 union fuse_file_args;
 217
 218 /** FUSE specific file data */
 219 struct fuse_file {
 220         /** Fuse connection for this file */
 221         struct fuse_mount *fm;
 222
 223         /* Argument space reserved for open/release */
 224         union fuse_file_args *args;
 225
 226         /** Kernel file handle guaranteed to be unique */
 227         u64 kh;
 228
 229         /** File handle used by userspace */
 230         u64 fh;
 231
 232         /** Node id of this file */
 233         u64 nodeid;
 234
 235         /** Refcount */
 236         refcount_t count;
 237
 238         /** FOPEN_* flags returned by open */
 239         u32 open_flags;
 240
 241         /** Entry on inode's write_files list */
 242         struct list_head write_entry;
 243
 244         /* Readdir related */
 245         struct {
 246                 /* Dir stream position */
 247                 loff_t pos;
 248
 249                 /* Offset in cache */
 250                 loff_t cache_off;
 251
 252                 /* Version of cache we are reading */
 253                 u64 version;
 254
 255         } readdir;
 256
 257         /** RB node to be linked on fuse_conn->polled_files */
 258         struct rb_node polled_node;
 259
 260         /** Wait queue head for poll */
 261         wait_queue_head_t poll_wait;
 262
 263         /** Does file hold a fi->iocachectr refcount? */
 264         enum { IOM_NONE, IOM_CACHED, IOM_UNCACHED } iomode;
 265
 266 #ifdef CONFIG_FUSE_PASSTHROUGH
 267         /** Reference to backing file in passthrough mode */
 268         struct file *passthrough;
 269         const struct cred *cred;
 270 #endif
 271
 272         /** Has flock been performed on this file? */
 273         bool flock:1;
 274 };
 275
 276 /** One input argument of a request */
 277 struct fuse_in_arg {
 278         unsigned size;
 279         const void *value;
 280 };
 281
 282 /** One output argument of a request */
 283 struct fuse_arg {
 284         unsigned size;
 285         void *value;
 286 };
 287
 288 /** FUSE folio descriptor */
 289 struct fuse_folio_desc {
 290         unsigned int length;
 291         unsigned int offset;
 292 };
 293
 294 struct fuse_args {
 295         uint64_t nodeid;
 296         uint32_t opcode;
 297         uint8_t in_numargs;
 298         uint8_t out_numargs;
 299         uint8_t ext_idx;
 300         bool force:1;
 301         bool noreply:1;
 302         bool nocreds:1;
 303         bool in_pages:1;
 304         bool out_pages:1;
 305         bool user_pages:1;
 306         bool out_argvar:1;
 307         bool page_zeroing:1;
 308         bool page_replace:1;
 309         bool may_block:1;
 310         bool is_ext:1;
 311         bool is_pinned:1;
 312         bool invalidate_vmap:1;
 313         struct fuse_in_arg in_args[3];
 314         struct fuse_arg out_args[2];
 315         void (*end)(struct fuse_mount *fm, struct fuse_args *args, int error);
 316         /* Used for kvec iter backed by vmalloc address */
 317         void *vmap_base;
 318 };
 319
 320 struct fuse_args_pages {
 321         struct fuse_args args;
 322         struct folio **folios;
 323         struct fuse_folio_desc *descs;
 324         unsigned int num_folios;
 325 };
 326
 327 struct fuse_release_args {
 328         struct fuse_args args;
 329         struct fuse_release_in inarg;
 330         struct inode *inode;
 331 };
 332
 333 union fuse_file_args {
 334         /* Used during open() */
 335         struct fuse_open_out open_outarg;
 336         /* Used during release() */
 337         struct fuse_release_args release_args;
 338 };
 339
 340 #define FUSE_ARGS(args) struct fuse_args args = {}
 341
 342 /** The request IO state (for asynchronous processing) */
 343 struct fuse_io_priv {
 344         struct kref refcnt;
 345         int async;
 346         spinlock_t lock;
 347         unsigned reqs;
 348         ssize_t bytes;
 349         size_t size;
 350         __u64 offset;
 351         bool write;
 352         bool should_dirty;
 353         int err;
 354         struct kiocb *iocb;
 355         struct completion *done;
 356         bool blocking;
 357 };
 358
 359 #define FUSE_IO_PRIV_SYNC(i) \
 360 {                                       \
 361         .refcnt = KREF_INIT(1),         \
 362         .async = 0,                     \
 363         .iocb = i,                      \
 364 }
 365
 366 /**
 367  * Request flags
 368  *
 369  * FR_ISREPLY:          set if the request has reply
 370  * FR_FORCE:            force sending of the request even if interrupted
 371  * FR_BACKGROUND:       request is sent in the background
 372  * FR_WAITING:          request is counted as "waiting"
 373  * FR_ABORTED:          the request was aborted
 374  * FR_INTERRUPTED:      the request has been interrupted
 375  * FR_LOCKED:           data is being copied to/from the request
 376  * FR_PENDING:          request is not yet in userspace
 377  * FR_SENT:             request is in userspace, waiting for an answer
 378  * FR_FINISHED:         request is finished
 379  * FR_PRIVATE:          request is on private list
 380  * FR_ASYNC:            request is asynchronous
 381  */
 382 enum fuse_req_flag {
 383         FR_ISREPLY,
 384         FR_FORCE,
 385         FR_BACKGROUND,
 386         FR_WAITING,
 387         FR_ABORTED,
 388         FR_INTERRUPTED,
 389         FR_LOCKED,
 390         FR_PENDING,
 391         FR_SENT,
 392         FR_FINISHED,
 393         FR_PRIVATE,
 394         FR_ASYNC,
 395 };
 396
 397 /**
 398  * A request to the client
 399  *
 400  * .waitq.lock protects the following fields:
 401  *   - FR_ABORTED
 402  *   - FR_LOCKED (may also be modified under fc->lock, tested under both)
 403  */
 404 struct fuse_req {
 405         /** This can be on either pending processing or io lists in
 406             fuse_conn */
 407         struct list_head list;
 408
 409         /** Entry on the interrupts list  */
 410         struct list_head intr_entry;
 411
 412         /* Input/output arguments */
 413         struct fuse_args *args;
 414
 415         /** refcount */
 416         refcount_t count;
 417
 418         /* Request flags, updated with test/set/clear_bit() */
 419         unsigned long flags;
 420
 421         /* The request input header */
 422         struct {
 423                 struct fuse_in_header h;
 424         } in;
 425
 426         /* The request output header */
 427         struct {
 428                 struct fuse_out_header h;
 429         } out;
 430
 431         /** Used to wake up the task waiting for completion of request*/
 432         wait_queue_head_t waitq;
 433
 434 #if IS_ENABLED(CONFIG_VIRTIO_FS)
 435         /** virtio-fs's physically contiguous buffer for in and out args */
 436         void *argbuf;
 437 #endif
 438
 439         /** fuse_mount this request belongs to */
 440         struct fuse_mount *fm;
 441 };
 442
 443 struct fuse_iqueue;
 444
 445 /**
 446  * Input queue callbacks
 447  *
 448  * Input queue signalling is device-specific.  For example, the /dev/fuse file
 449  * uses fiq->waitq and fasync to wake processes that are waiting on queue
 450  * readiness.  These callbacks allow other device types to respond to input
 451  * queue activity.
 452  */
 453 struct fuse_iqueue_ops {
 454         /**
 455          * Send one forget
 456          */
 457         void (*send_forget)(struct fuse_iqueue *fiq, struct fuse_forget_link *link);
 458
 459         /**
 460          * Send interrupt for request
 461          */
 462         void (*send_interrupt)(struct fuse_iqueue *fiq, struct fuse_req *req);
 463
 464         /**
 465          * Send one request
 466          */
 467         void (*send_req)(struct fuse_iqueue *fiq, struct fuse_req *req);
 468
 469         /**
 470          * Clean up when fuse_iqueue is destroyed
 471          */
 472         void (*release)(struct fuse_iqueue *fiq);
 473 };
 474
 475 /** /dev/fuse input queue operations */
 476 extern const struct fuse_iqueue_ops fuse_dev_fiq_ops;
 477
 478 struct fuse_iqueue {
 479         /** Connection established */
 480         unsigned connected;
 481
 482         /** Lock protecting accesses to members of this structure */
 483         spinlock_t lock;
 484
 485         /** Readers of the connection are waiting on this */
 486         wait_queue_head_t waitq;
 487
 488         /** The next unique request id */
 489         u64 reqctr;
 490
 491         /** The list of pending requests */
 492         struct list_head pending;
 493
 494         /** Pending interrupts */
 495         struct list_head interrupts;
 496
 497         /** Queue of pending forgets */
 498         struct fuse_forget_link forget_list_head;
 499         struct fuse_forget_link *forget_list_tail;
 500
 501         /** Batching of FORGET requests (positive indicates FORGET batch) */
 502         int forget_batch;
 503
 504         /** O_ASYNC requests */
 505         struct fasync_struct *fasync;
 506
 507         /** Device-specific callbacks */
 508         const struct fuse_iqueue_ops *ops;
 509
 510         /** Device-specific state */
 511         void *priv;
 512 };
 513
 514 #define FUSE_PQ_HASH_BITS 8
 515 #define FUSE_PQ_HASH_SIZE (1 << FUSE_PQ_HASH_BITS)
 516
 517 struct fuse_pqueue {
 518         /** Connection established */
 519         unsigned connected;
 520
 521         /** Lock protecting accessess to  members of this structure */
 522         spinlock_t lock;
 523
 524         /** Hash table of requests being processed */
 525         struct list_head *processing;
 526
 527         /** The list of requests under I/O */
 528         struct list_head io;
 529 };
 530
 531 /**
 532  * Fuse device instance
 533  */
 534 struct fuse_dev {
 535         /** Fuse connection for this device */
 536         struct fuse_conn *fc;
 537
 538         /** Processing queue */
 539         struct fuse_pqueue pq;
 540
 541         /** list entry on fc->devices */
 542         struct list_head entry;
 543 };
 544
 545 enum fuse_dax_mode {
 546         FUSE_DAX_INODE_DEFAULT, /* default */
 547         FUSE_DAX_ALWAYS,        /* "-o dax=always" */
 548         FUSE_DAX_NEVER,         /* "-o dax=never" */
 549         FUSE_DAX_INODE_USER,    /* "-o dax=inode" */
 550 };
 551
 552 static inline bool fuse_is_inode_dax_mode(enum fuse_dax_mode mode)
 553 {
 554         return mode == FUSE_DAX_INODE_DEFAULT || mode == FUSE_DAX_INODE_USER;
 555 }
 556
 557 struct fuse_fs_context {
 558         int fd;
 559         struct file *file;
 560         unsigned int rootmode;
 561         kuid_t user_id;
 562         kgid_t group_id;
 563         bool is_bdev:1;
 564         bool fd_present:1;
 565         bool rootmode_present:1;
 566         bool user_id_present:1;
 567         bool group_id_present:1;
 568         bool default_permissions:1;
 569         bool allow_other:1;
 570         bool destroy:1;
 571         bool no_control:1;
 572         bool no_force_umount:1;
 573         bool legacy_opts_show:1;
 574         enum fuse_dax_mode dax_mode;
 575         unsigned int max_read;
 576         unsigned int blksize;
 577         const char *subtype;
 578
 579         /* DAX device, may be NULL */
 580         struct dax_device *dax_dev;
 581
 582         /* fuse_dev pointer to fill in, should contain NULL on entry */
 583         void **fudptr;
 584 };
 585
 586 struct fuse_sync_bucket {
 587         /* count is a possible scalability bottleneck */
 588         atomic_t count;
 589         wait_queue_head_t waitq;
 590         struct rcu_head rcu;
 591 };
 592
 593 /**
 594  * A Fuse connection.
 595  *
 596  * This structure is created, when the root filesystem is mounted, and
 597  * is destroyed, when the client device is closed and the last
 598  * fuse_mount is destroyed.
 599  */
 600 struct fuse_conn {
 601         /** Lock protecting accessess to  members of this structure */
 602         spinlock_t lock;
 603
 604         /** Refcount */
 605         refcount_t count;
 606
 607         /** Number of fuse_dev's */
 608         atomic_t dev_count;
 609
 610         struct rcu_head rcu;
 611
 612         /** The user id for this mount */
 613         kuid_t user_id;
 614
 615         /** The group id for this mount */
 616         kgid_t group_id;
 617
 618         /** The pid namespace for this mount */
 619         struct pid_namespace *pid_ns;
 620
 621         /** The user namespace for this mount */
 622         struct user_namespace *user_ns;
 623
 624         /** Maximum read size */
 625         unsigned max_read;
 626
 627         /** Maximum write size */
 628         unsigned max_write;
 629
 630         /** Maximum number of pages that can be used in a single request */
 631         unsigned int max_pages;
 632
 633         /** Constrain ->max_pages to this value during feature negotiation */
 634         unsigned int max_pages_limit;
 635
 636         /** Input queue */
 637         struct fuse_iqueue iq;
 638
 639         /** The next unique kernel file handle */
 640         atomic64_t khctr;
 641
 642         /** rbtree of fuse_files waiting for poll events indexed by ph */
 643         struct rb_root polled_files;
 644
 645         /** Maximum number of outstanding background requests */
 646         unsigned max_background;
 647
 648         /** Number of background requests at which congestion starts */
 649         unsigned congestion_threshold;
 650
 651         /** Number of requests currently in the background */
 652         unsigned num_background;
 653
 654         /** Number of background requests currently queued for userspace */
 655         unsigned active_background;
 656
 657         /** The list of background requests set aside for later queuing */
 658         struct list_head bg_queue;
 659
 660         /** Protects: max_background, congestion_threshold, num_background,
 661          * active_background, bg_queue, blocked */
 662         spinlock_t bg_lock;
 663
 664         /** Flag indicating that INIT reply has been received. Allocating
 665          * any fuse request will be suspended until the flag is set */
 666         int initialized;
 667
 668         /** Flag indicating if connection is blocked.  This will be
 669             the case before the INIT reply is received, and if there
 670             are too many outstading backgrounds requests */
 671         int blocked;
 672
 673         /** waitq for blocked connection */
 674         wait_queue_head_t blocked_waitq;
 675
 676         /** Connection established, cleared on umount, connection
 677             abort and device release */
 678         unsigned connected;
 679
 680         /** Connection aborted via sysfs */
 681         bool aborted;
 682
 683         /** Connection failed (version mismatch).  Cannot race with
 684             setting other bitfields since it is only set once in INIT
 685             reply, before any other request, and never cleared */
 686         unsigned conn_error:1;
 687
 688         /** Connection successful.  Only set in INIT */
 689         unsigned conn_init:1;
 690
 691         /** Do readahead asynchronously?  Only set in INIT */
 692         unsigned async_read:1;
 693
 694         /** Return an unique read error after abort.  Only set in INIT */
 695         unsigned abort_err:1;
 696
 697         /** Do not send separate SETATTR request before open(O_TRUNC)  */
 698         unsigned atomic_o_trunc:1;
 699
 700         /** Filesystem supports NFS exporting.  Only set in INIT */
 701         unsigned export_support:1;
 702
 703         /** write-back cache policy (default is write-through) */
 704         unsigned writeback_cache:1;
 705
 706         /** allow parallel lookups and readdir (default is serialized) */
 707         unsigned parallel_dirops:1;
 708
 709         /** handle fs handles killing suid/sgid/cap on write/chown/trunc */
 710         unsigned handle_killpriv:1;
 711
 712         /** cache READLINK responses in page cache */
 713         unsigned cache_symlinks:1;
 714
 715         /* show legacy mount options */
 716         unsigned int legacy_opts_show:1;
 717
 718         /*
 719          * fs kills suid/sgid/cap on write/chown/trunc. suid is killed on
 720          * write/trunc only if caller did not have CAP_FSETID.  sgid is killed
 721          * on write/truncate only if caller did not have CAP_FSETID as well as
 722          * file has group execute permission.
 723          */
 724         unsigned handle_killpriv_v2:1;
 725
 726         /*
 727          * The following bitfields are only for optimization purposes
 728          * and hence races in setting them will not cause malfunction
 729          */
 730
 731         /** Is open/release not implemented by fs? */
 732         unsigned no_open:1;
 733
 734         /** Is opendir/releasedir not implemented by fs? */
 735         unsigned no_opendir:1;
 736
 737         /** Is fsync not implemented by fs? */
 738         unsigned no_fsync:1;
 739
 740         /** Is fsyncdir not implemented by fs? */
 741         unsigned no_fsyncdir:1;
 742
 743         /** Is flush not implemented by fs? */
 744         unsigned no_flush:1;
 745
 746         /** Is setxattr not implemented by fs? */
 747         unsigned no_setxattr:1;
 748
 749         /** Does file server support extended setxattr */
 750         unsigned setxattr_ext:1;
 751
 752         /** Is getxattr not implemented by fs? */
 753         unsigned no_getxattr:1;
 754
 755         /** Is listxattr not implemented by fs? */
 756         unsigned no_listxattr:1;
 757
 758         /** Is removexattr not implemented by fs? */
 759         unsigned no_removexattr:1;
 760
 761         /** Are posix file locking primitives not implemented by fs? */
 762         unsigned no_lock:1;
 763
 764         /** Is access not implemented by fs? */
 765         unsigned no_access:1;
 766
 767         /** Is create not implemented by fs? */
 768         unsigned no_create:1;
 769
 770         /** Is interrupt not implemented by fs? */
 771         unsigned no_interrupt:1;
 772
 773         /** Is bmap not implemented by fs? */
 774         unsigned no_bmap:1;
 775
 776         /** Is poll not implemented by fs? */
 777         unsigned no_poll:1;
 778
 779         /** Do multi-page cached writes */
 780         unsigned big_writes:1;
 781
 782         /** Don't apply umask to creation modes */
 783         unsigned dont_mask:1;
 784
 785         /** Are BSD file locking primitives not implemented by fs? */
 786         unsigned no_flock:1;
 787
 788         /** Is fallocate not implemented by fs? */
 789         unsigned no_fallocate:1;
 790
 791         /** Is rename with flags implemented by fs? */
 792         unsigned no_rename2:1;
 793
 794         /** Use enhanced/automatic page cache invalidation. */
 795         unsigned auto_inval_data:1;
 796
 797         /** Filesystem is fully responsible for page cache invalidation. */
 798         unsigned explicit_inval_data:1;
 799
 800         /** Does the filesystem support readdirplus? */
 801         unsigned do_readdirplus:1;
 802
 803         /** Does the filesystem want adaptive readdirplus? */
 804         unsigned readdirplus_auto:1;
 805
 806         /** Does the filesystem support asynchronous direct-IO submission? */
 807         unsigned async_dio:1;
 808
 809         /** Is lseek not implemented by fs? */
 810         unsigned no_lseek:1;
 811
 812         /** Does the filesystem support posix acls? */
 813         unsigned posix_acl:1;
 814
 815         /** Check permissions based on the file mode or not? */
 816         unsigned default_permissions:1;
 817
 818         /** Allow other than the mounter user to access the filesystem ? */
 819         unsigned allow_other:1;
 820
 821         /** Does the filesystem support copy_file_range? */
 822         unsigned no_copy_file_range:1;
 823
 824         /* Send DESTROY request */
 825         unsigned int destroy:1;
 826
 827         /* Delete dentries that have gone stale */
 828         unsigned int delete_stale:1;
 829
 830         /** Do not create entry in fusectl fs */
 831         unsigned int no_control:1;
 832
 833         /** Do not allow MNT_FORCE umount */
 834         unsigned int no_force_umount:1;
 835
 836         /* Auto-mount submounts announced by the server */
 837         unsigned int auto_submounts:1;
 838
 839         /* Propagate syncfs() to server */
 840         unsigned int sync_fs:1;
 841
 842         /* Initialize security xattrs when creating a new inode */
 843         unsigned int init_security:1;
 844
 845         /* Add supplementary group info when creating a new inode */
 846         unsigned int create_supp_group:1;
 847
 848         /* Does the filesystem support per inode DAX? */
 849         unsigned int inode_dax:1;
 850
 851         /* Is tmpfile not implemented by fs? */
 852         unsigned int no_tmpfile:1;
 853
 854         /* Relax restrictions to allow shared mmap in FOPEN_DIRECT_IO mode */
 855         unsigned int direct_io_allow_mmap:1;
 856
 857         /* Is statx not implemented by fs? */
 858         unsigned int no_statx:1;
 859
 860         /** Passthrough support for read/write IO */
 861         unsigned int passthrough:1;
 862
 863         /* Use pages instead of pointer for kernel I/O */
 864         unsigned int use_pages_for_kvec_io:1;
 865
 866         /** Maximum stack depth for passthrough backing files */
 867         int max_stack_depth;
 868
 869         /** The number of requests waiting for completion */
 870         atomic_t num_waiting;
 871
 872         /** Negotiated minor version */
 873         unsigned minor;
 874
 875         /** Entry on the fuse_conn_list */
 876         struct list_head entry;
 877
 878         /** Device ID from the root super block */
 879         dev_t dev;
 880
 881         /** Dentries in the control filesystem */
 882         struct dentry *ctl_dentry[FUSE_CTL_NUM_DENTRIES];
 883
 884         /** number of dentries used in the above array */
 885         int ctl_ndents;
 886
 887         /** Key for lock owner ID scrambling */
 888         u32 scramble_key[4];
 889
 890         /** Version counter for attribute changes */
 891         atomic64_t attr_version;
 892
 893         /** Version counter for evict inode */
 894         atomic64_t evict_ctr;
 895
 896         /** Called on final put */
 897         void (*release)(struct fuse_conn *);
 898
 899         /**
 900          * Read/write semaphore to hold when accessing the sb of any
 901          * fuse_mount belonging to this connection
 902          */
 903         struct rw_semaphore killsb;
 904
 905         /** List of device instances belonging to this connection */
 906         struct list_head devices;
 907
 908 #ifdef CONFIG_FUSE_DAX
 909         /* Dax mode */
 910         enum fuse_dax_mode dax_mode;
 911
 912         /* Dax specific conn data, non-NULL if DAX is enabled */
 913         struct fuse_conn_dax *dax;
 914 #endif
 915
 916         /** List of filesystems using this connection */
 917         struct list_head mounts;
 918
 919         /* New writepages go into this bucket */
 920         struct fuse_sync_bucket __rcu *curr_bucket;
 921
 922 #ifdef CONFIG_FUSE_PASSTHROUGH
 923         /** IDR for backing files ids */
 924         struct idr backing_files_map;
 925 #endif
 926 };
 927
 928 /*
 929  * Represents a mounted filesystem, potentially a submount.
 930  *
 931  * This object allows sharing a fuse_conn between separate mounts to
 932  * allow submounts with dedicated superblocks and thus separate device
 933  * IDs.
 934  */
 935 struct fuse_mount {
 936         /* Underlying (potentially shared) connection to the FUSE server */
 937         struct fuse_conn *fc;
 938
 939         /*
 940          * Super block for this connection (fc->killsb must be held when
 941          * accessing this).
 942          */
 943         struct super_block *sb;
 944
 945         /* Entry on fc->mounts */
 946         struct list_head fc_entry;
 947         struct rcu_head rcu;
 948 };
 949
 950 static inline struct fuse_mount *get_fuse_mount_super(struct super_block *sb)
 951 {
 952         return sb->s_fs_info;
 953 }
 954
 955 static inline struct fuse_conn *get_fuse_conn_super(struct super_block *sb)
 956 {
 957         return get_fuse_mount_super(sb)->fc;
 958 }
 959
 960 static inline struct fuse_mount *get_fuse_mount(struct inode *inode)
 961 {
 962         return get_fuse_mount_super(inode->i_sb);
 963 }
 964
 965 static inline struct fuse_conn *get_fuse_conn(struct inode *inode)
 966 {
 967         return get_fuse_mount_super(inode->i_sb)->fc;
 968 }
 969
 970 static inline struct fuse_inode *get_fuse_inode(struct inode *inode)
 971 {
 972         return container_of(inode, struct fuse_inode, inode);
 973 }
 974
 975 static inline u64 get_node_id(struct inode *inode)
 976 {
 977         return get_fuse_inode(inode)->nodeid;
 978 }
 979
 980 static inline int invalid_nodeid(u64 nodeid)
 981 {
 982         return !nodeid || nodeid == FUSE_ROOT_ID;
 983 }
 984
 985 static inline u64 fuse_get_attr_version(struct fuse_conn *fc)
 986 {
 987         return atomic64_read(&fc->attr_version);
 988 }
 989
 990 static inline u64 fuse_get_evict_ctr(struct fuse_conn *fc)
 991 {
 992         return atomic64_read(&fc->evict_ctr);
 993 }
 994
 995 static inline bool fuse_stale_inode(const struct inode *inode, int generation,
 996                                     struct fuse_attr *attr)
 997 {
 998         return inode->i_generation != generation ||
 999                 inode_wrong_type(inode, attr->mode);
1000 }
1001
1002 static inline void fuse_make_bad(struct inode *inode)
1003 {
1004         set_bit(FUSE_I_BAD, &get_fuse_inode(inode)->state);
1005 }
1006
1007 static inline bool fuse_is_bad(struct inode *inode)
1008 {
1009         return unlikely(test_bit(FUSE_I_BAD, &get_fuse_inode(inode)->state));
1010 }
1011
1012 static inline struct folio **fuse_folios_alloc(unsigned int nfolios, gfp_t flags,
1013                                                struct fuse_folio_desc **desc)
1014 {
1015         struct folio **folios;
1016
1017         folios = kzalloc(nfolios * (sizeof(struct folio *) +
1018                                     sizeof(struct fuse_folio_desc)), flags);
1019         *desc = (void *) (folios + nfolios);
1020
1021         return folios;
1022 }
1023
1024 static inline void fuse_folio_descs_length_init(struct fuse_folio_desc *descs,
1025                                                 unsigned int index,
1026                                                 unsigned int nr_folios)
1027 {
1028         int i;
1029
1030         for (i = index; i < index + nr_folios; i++)
1031                 descs[i].length = PAGE_SIZE - descs[i].offset;
1032 }
1033
1034 static inline void fuse_sync_bucket_dec(struct fuse_sync_bucket *bucket)
1035 {
1036         /* Need RCU protection to prevent use after free after the decrement */
1037         rcu_read_lock();
1038         if (atomic_dec_and_test(&bucket->count))
1039                 wake_up(&bucket->waitq);
1040         rcu_read_unlock();
1041 }
1042
1043 /** Device operations */
1044 extern const struct file_operations fuse_dev_operations;
1045
1046 extern const struct dentry_operations fuse_dentry_operations;
1047 extern const struct dentry_operations fuse_root_dentry_operations;
1048
1049 /**
1050  * Get a filled in inode
1051  */
1052 struct inode *fuse_iget(struct super_block *sb, u64 nodeid,
1053                         int generation, struct fuse_attr *attr,
1054                         u64 attr_valid, u64 attr_version,
1055                         u64 evict_ctr);
1056
1057 int fuse_lookup_name(struct super_block *sb, u64 nodeid, const struct qstr *name,
1058                      struct fuse_entry_out *outarg, struct inode **inode);
1059
1060 /**
1061  * Send FORGET command
1062  */
1063 void fuse_queue_forget(struct fuse_conn *fc, struct fuse_forget_link *forget,
1064                        u64 nodeid, u64 nlookup);
1065
1066 struct fuse_forget_link *fuse_alloc_forget(void);
1067
1068 /*
1069  * Initialize READ or READDIR request
1070  */
1071 struct fuse_io_args {
1072         union {
1073                 struct {
1074                         struct fuse_read_in in;
1075                         u64 attr_ver;
1076                 } read;
1077                 struct {
1078                         struct fuse_write_in in;
1079                         struct fuse_write_out out;
1080                         bool folio_locked;
1081                 } write;
1082         };
1083         struct fuse_args_pages ap;
1084         struct fuse_io_priv *io;
1085         struct fuse_file *ff;
1086 };
1087
1088 void fuse_read_args_fill(struct fuse_io_args *ia, struct file *file, loff_t pos,
1089                          size_t count, int opcode);
1090
1091
1092 struct fuse_file *fuse_file_alloc(struct fuse_mount *fm, bool release);
1093 void fuse_file_free(struct fuse_file *ff);
1094 int fuse_finish_open(struct inode *inode, struct file *file);
1095
1096 void fuse_sync_release(struct fuse_inode *fi, struct fuse_file *ff,
1097                        unsigned int flags);
1098
1099 /**
1100  * Send RELEASE or RELEASEDIR request
1101  */
1102 void fuse_release_common(struct file *file, bool isdir);
1103
1104 /**
1105  * Send FSYNC or FSYNCDIR request
1106  */
1107 int fuse_fsync_common(struct file *file, loff_t start, loff_t end,
1108                       int datasync, int opcode);
1109
1110 /**
1111  * Notify poll wakeup
1112  */
1113 int fuse_notify_poll_wakeup(struct fuse_conn *fc,
1114                             struct fuse_notify_poll_wakeup_out *outarg);
1115
1116 /**
1117  * Initialize file operations on a regular file
1118  */
1119 void fuse_init_file_inode(struct inode *inode, unsigned int flags);
1120
1121 /**
1122  * Initialize inode operations on regular files and special files
1123  */
1124 void fuse_init_common(struct inode *inode);
1125
1126 /**
1127  * Initialize inode and file operations on a directory
1128  */
1129 void fuse_init_dir(struct inode *inode);
1130
1131 /**
1132  * Initialize inode operations on a symlink
1133  */
1134 void fuse_init_symlink(struct inode *inode);
1135
1136 /**
1137  * Change attributes of an inode
1138  */
1139 void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr,
1140                             struct fuse_statx *sx,
1141                             u64 attr_valid, u64 attr_version);
1142
1143 void fuse_change_attributes_common(struct inode *inode, struct fuse_attr *attr,
1144                                    struct fuse_statx *sx,
1145                                    u64 attr_valid, u32 cache_mask,
1146                                    u64 evict_ctr);
1147
1148 u32 fuse_get_cache_mask(struct inode *inode);
1149
1150 /**
1151  * Initialize the client device
1152  */
1153 int fuse_dev_init(void);
1154
1155 /**
1156  * Cleanup the client device
1157  */
1158 void fuse_dev_cleanup(void);
1159
1160 int fuse_ctl_init(void);
1161 void __exit fuse_ctl_cleanup(void);
1162
1163 /**
1164  * Simple request sending that does request allocation and freeing
1165  */
1166 ssize_t __fuse_simple_request(struct mnt_idmap *idmap,
1167                               struct fuse_mount *fm,
1168                               struct fuse_args *args);
1169
1170 static inline ssize_t fuse_simple_request(struct fuse_mount *fm, struct fuse_args *args)
1171 {
1172         return __fuse_simple_request(&invalid_mnt_idmap, fm, args);
1173 }
1174
1175 static inline ssize_t fuse_simple_idmap_request(struct mnt_idmap *idmap,
1176                                                 struct fuse_mount *fm,
1177                                                 struct fuse_args *args)
1178 {
1179         return __fuse_simple_request(idmap, fm, args);
1180 }
1181
1182 int fuse_simple_background(struct fuse_mount *fm, struct fuse_args *args,
1183                            gfp_t gfp_flags);
1184
1185 /**
1186  * End a finished request
1187  */
1188 void fuse_request_end(struct fuse_req *req);
1189
1190 /* Abort all requests */
1191 void fuse_abort_conn(struct fuse_conn *fc);
1192 void fuse_wait_aborted(struct fuse_conn *fc);
1193
1194 /**
1195  * Invalidate inode attributes
1196  */
1197
1198 /* Attributes possibly changed on data modification */
1199 #define FUSE_STATX_MODIFY       (STATX_MTIME | STATX_CTIME | STATX_BLOCKS)
1200
1201 /* Attributes possibly changed on data and/or size modification */
1202 #define FUSE_STATX_MODSIZE      (FUSE_STATX_MODIFY | STATX_SIZE)
1203
1204 void fuse_invalidate_attr(struct inode *inode);
1205 void fuse_invalidate_attr_mask(struct inode *inode, u32 mask);
1206
1207 void fuse_invalidate_entry_cache(struct dentry *entry);
1208
1209 void fuse_invalidate_atime(struct inode *inode);
1210
1211 u64 fuse_time_to_jiffies(u64 sec, u32 nsec);
1212 #define ATTR_TIMEOUT(o) \
1213         fuse_time_to_jiffies((o)->attr_valid, (o)->attr_valid_nsec)
1214
1215 void fuse_change_entry_timeout(struct dentry *entry, struct fuse_entry_out *o);
1216
1217 /**
1218  * Acquire reference to fuse_conn
1219  */
1220 struct fuse_conn *fuse_conn_get(struct fuse_conn *fc);
1221
1222 /**
1223  * Initialize fuse_conn
1224  */
1225 void fuse_conn_init(struct fuse_conn *fc, struct fuse_mount *fm,
1226                     struct user_namespace *user_ns,
1227                     const struct fuse_iqueue_ops *fiq_ops, void *fiq_priv);
1228
1229 /**
1230  * Release reference to fuse_conn
1231  */
1232 void fuse_conn_put(struct fuse_conn *fc);
1233
1234 struct fuse_dev *fuse_dev_alloc_install(struct fuse_conn *fc);
1235 struct fuse_dev *fuse_dev_alloc(void);
1236 void fuse_dev_install(struct fuse_dev *fud, struct fuse_conn *fc);
1237 void fuse_dev_free(struct fuse_dev *fud);
1238 void fuse_send_init(struct fuse_mount *fm);
1239
1240 /**
1241  * Fill in superblock and initialize fuse connection
1242  * @sb: partially-initialized superblock to fill in
1243  * @ctx: mount context
1244  */
1245 int fuse_fill_super_common(struct super_block *sb, struct fuse_fs_context *ctx);
1246
1247 /*
1248  * Remove the mount from the connection
1249  *
1250  * Returns whether this was the last mount
1251  */
1252 bool fuse_mount_remove(struct fuse_mount *fm);
1253
1254 /*
1255  * Setup context ops for submounts
1256  */
1257 int fuse_init_fs_context_submount(struct fs_context *fsc);
1258
1259 /*
1260  * Shut down the connection (possibly sending DESTROY request).
1261  */
1262 void fuse_conn_destroy(struct fuse_mount *fm);
1263
1264 /* Drop the connection and free the fuse mount */
1265 void fuse_mount_destroy(struct fuse_mount *fm);
1266
1267 /**
1268  * Add connection to control filesystem
1269  */
1270 int fuse_ctl_add_conn(struct fuse_conn *fc);
1271
1272 /**
1273  * Remove connection from control filesystem
1274  */
1275 void fuse_ctl_remove_conn(struct fuse_conn *fc);
1276
1277 /**
1278  * Is file type valid?
1279  */
1280 int fuse_valid_type(int m);
1281
1282 bool fuse_invalid_attr(struct fuse_attr *attr);
1283
1284 /**
1285  * Is current process allowed to perform filesystem operation?
1286  */
1287 bool fuse_allow_current_process(struct fuse_conn *fc);
1288
1289 u64 fuse_lock_owner_id(struct fuse_conn *fc, fl_owner_t id);
1290
1291 void fuse_flush_time_update(struct inode *inode);
1292 void fuse_update_ctime(struct inode *inode);
1293
1294 int fuse_update_attributes(struct inode *inode, struct file *file, u32 mask);
1295
1296 void fuse_flush_writepages(struct inode *inode);
1297
1298 void fuse_set_nowrite(struct inode *inode);
1299 void fuse_release_nowrite(struct inode *inode);
1300
1301 /**
1302  * Scan all fuse_mounts belonging to fc to find the first where
1303  * ilookup5() returns a result.  Return that result and the
1304  * respective fuse_mount in *fm (unless fm is NULL).
1305  *
1306  * The caller must hold fc->killsb.
1307  */
1308 struct inode *fuse_ilookup(struct fuse_conn *fc, u64 nodeid,
1309                            struct fuse_mount **fm);
1310
1311 /**
1312  * File-system tells the kernel to invalidate cache for the given node id.
1313  */
1314 int fuse_reverse_inval_inode(struct fuse_conn *fc, u64 nodeid,
1315                              loff_t offset, loff_t len);
1316
1317 /**
1318  * File-system tells the kernel to invalidate parent attributes and
1319  * the dentry matching parent/name.
1320  *
1321  * If the child_nodeid is non-zero and:
1322  *    - matches the inode number for the dentry matching parent/name,
1323  *    - is not a mount point
1324  *    - is a file or oan empty directory
1325  * then the dentry is unhashed (d_delete()).
1326  */
1327 int fuse_reverse_inval_entry(struct fuse_conn *fc, u64 parent_nodeid,
1328                              u64 child_nodeid, struct qstr *name, u32 flags);
1329
1330 int fuse_do_open(struct fuse_mount *fm, u64 nodeid, struct file *file,
1331                  bool isdir);
1332
1333 /**
1334  * fuse_direct_io() flags
1335  */
1336
1337 /** If set, it is WRITE; otherwise - READ */
1338 #define FUSE_DIO_WRITE (1 << 0)
1339
1340 /** CUSE pass fuse_direct_io() a file which f_mapping->host is not from FUSE */
1341 #define FUSE_DIO_CUSE  (1 << 1)
1342
1343 ssize_t fuse_direct_io(struct fuse_io_priv *io, struct iov_iter *iter,
1344                        loff_t *ppos, int flags);
1345 long fuse_do_ioctl(struct file *file, unsigned int cmd, unsigned long arg,
1346                    unsigned int flags);
1347 long fuse_ioctl_common(struct file *file, unsigned int cmd,
1348                        unsigned long arg, unsigned int flags);
1349 __poll_t fuse_file_poll(struct file *file, poll_table *wait);
1350 int fuse_dev_release(struct inode *inode, struct file *file);
1351
1352 bool fuse_write_update_attr(struct inode *inode, loff_t pos, ssize_t written);
1353
1354 int fuse_flush_times(struct inode *inode, struct fuse_file *ff);
1355 int fuse_write_inode(struct inode *inode, struct writeback_control *wbc);
1356
1357 int fuse_do_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
1358                     struct iattr *attr, struct file *file);
1359
1360 void fuse_set_initialized(struct fuse_conn *fc);
1361
1362 void fuse_unlock_inode(struct inode *inode, bool locked);
1363 bool fuse_lock_inode(struct inode *inode);
1364
1365 int fuse_setxattr(struct inode *inode, const char *name, const void *value,
1366                   size_t size, int flags, unsigned int extra_flags);
1367 ssize_t fuse_getxattr(struct inode *inode, const char *name, void *value,
1368                       size_t size);
1369 ssize_t fuse_listxattr(struct dentry *entry, char *list, size_t size);
1370 int fuse_removexattr(struct inode *inode, const char *name);
1371 extern const struct xattr_handler * const fuse_xattr_handlers[];
1372
1373 struct posix_acl;
1374 struct posix_acl *fuse_get_inode_acl(struct inode *inode, int type, bool rcu);
1375 struct posix_acl *fuse_get_acl(struct mnt_idmap *idmap,
1376                                struct dentry *dentry, int type);
1377 int fuse_set_acl(struct mnt_idmap *, struct dentry *dentry,
1378                  struct posix_acl *acl, int type);
1379
1380 /* readdir.c */
1381 int fuse_readdir(struct file *file, struct dir_context *ctx);
1382
1383 /**
1384  * Return the number of bytes in an arguments list
1385  */
1386 unsigned int fuse_len_args(unsigned int numargs, struct fuse_arg *args);
1387
1388 /**
1389  * Get the next unique ID for a request
1390  */
1391 u64 fuse_get_unique(struct fuse_iqueue *fiq);
1392 void fuse_free_conn(struct fuse_conn *fc);
1393
1394 /* dax.c */
1395
1396 #define FUSE_IS_DAX(inode) (IS_ENABLED(CONFIG_FUSE_DAX) && IS_DAX(inode))
1397
1398 ssize_t fuse_dax_read_iter(struct kiocb *iocb, struct iov_iter *to);
1399 ssize_t fuse_dax_write_iter(struct kiocb *iocb, struct iov_iter *from);
1400 int fuse_dax_mmap(struct file *file, struct vm_area_struct *vma);
1401 int fuse_dax_break_layouts(struct inode *inode, u64 dmap_start, u64 dmap_end);
1402 int fuse_dax_conn_alloc(struct fuse_conn *fc, enum fuse_dax_mode mode,
1403                         struct dax_device *dax_dev);
1404 void fuse_dax_conn_free(struct fuse_conn *fc);
1405 bool fuse_dax_inode_alloc(struct super_block *sb, struct fuse_inode *fi);
1406 void fuse_dax_inode_init(struct inode *inode, unsigned int flags);
1407 void fuse_dax_inode_cleanup(struct inode *inode);
1408 void fuse_dax_dontcache(struct inode *inode, unsigned int flags);
1409 bool fuse_dax_check_alignment(struct fuse_conn *fc, unsigned int map_alignment);
1410 void fuse_dax_cancel_work(struct fuse_conn *fc);
1411
1412 /* ioctl.c */
1413 long fuse_file_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
1414 long fuse_file_compat_ioctl(struct file *file, unsigned int cmd,
1415                             unsigned long arg);
1416 int fuse_fileattr_get(struct dentry *dentry, struct fileattr *fa);
1417 int fuse_fileattr_set(struct mnt_idmap *idmap,
1418                       struct dentry *dentry, struct fileattr *fa);
1419
1420 /* iomode.c */
1421 int fuse_file_cached_io_open(struct inode *inode, struct fuse_file *ff);
1422 int fuse_inode_uncached_io_start(struct fuse_inode *fi,
1423                                  struct fuse_backing *fb);
1424 void fuse_inode_uncached_io_end(struct fuse_inode *fi);
1425
1426 int fuse_file_io_open(struct file *file, struct inode *inode);
1427 void fuse_file_io_release(struct fuse_file *ff, struct inode *inode);
1428
1429 /* file.c */
1430 struct fuse_file *fuse_file_open(struct fuse_mount *fm, u64 nodeid,
1431                                  unsigned int open_flags, bool isdir);
1432 void fuse_file_release(struct inode *inode, struct fuse_file *ff,
1433                        unsigned int open_flags, fl_owner_t id, bool isdir);
1434
1435 /* passthrough.c */
1436 static inline struct fuse_backing *fuse_inode_backing(struct fuse_inode *fi)
1437 {
1438 #ifdef CONFIG_FUSE_PASSTHROUGH
1439         return READ_ONCE(fi->fb);
1440 #else
1441         return NULL;
1442 #endif
1443 }
1444
1445 static inline struct fuse_backing *fuse_inode_backing_set(struct fuse_inode *fi,
1446                                                           struct fuse_backing *fb)
1447 {
1448 #ifdef CONFIG_FUSE_PASSTHROUGH
1449         return xchg(&fi->fb, fb);
1450 #else
1451         return NULL;
1452 #endif
1453 }
1454
1455 #ifdef CONFIG_FUSE_PASSTHROUGH
1456 struct fuse_backing *fuse_backing_get(struct fuse_backing *fb);
1457 void fuse_backing_put(struct fuse_backing *fb);
1458 #else
1459
1460 static inline struct fuse_backing *fuse_backing_get(struct fuse_backing *fb)
1461 {
1462         return NULL;
1463 }
1464
1465 static inline void fuse_backing_put(struct fuse_backing *fb)
1466 {
1467 }
1468 #endif
1469
1470 void fuse_backing_files_init(struct fuse_conn *fc);
1471 void fuse_backing_files_free(struct fuse_conn *fc);
1472 int fuse_backing_open(struct fuse_conn *fc, struct fuse_backing_map *map);
1473 int fuse_backing_close(struct fuse_conn *fc, int backing_id);
1474
1475 struct fuse_backing *fuse_passthrough_open(struct file *file,
1476                                            struct inode *inode,
1477                                            int backing_id);
1478 void fuse_passthrough_release(struct fuse_file *ff, struct fuse_backing *fb);
1479
1480 static inline struct file *fuse_file_passthrough(struct fuse_file *ff)
1481 {
1482 #ifdef CONFIG_FUSE_PASSTHROUGH
1483         return ff->passthrough;
1484 #else
1485         return NULL;
1486 #endif
1487 }
1488
1489 ssize_t fuse_passthrough_read_iter(struct kiocb *iocb, struct iov_iter *iter);
1490 ssize_t fuse_passthrough_write_iter(struct kiocb *iocb, struct iov_iter *iter);
1491 ssize_t fuse_passthrough_splice_read(struct file *in, loff_t *ppos,
1492                                      struct pipe_inode_info *pipe,
1493                                      size_t len, unsigned int flags);
1494 ssize_t fuse_passthrough_splice_write(struct pipe_inode_info *pipe,
1495                                       struct file *out, loff_t *ppos,
1496                                       size_t len, unsigned int flags);
1497 ssize_t fuse_passthrough_mmap(struct file *file, struct vm_area_struct *vma);
1498
1499 #ifdef CONFIG_SYSCTL
1500 extern int fuse_sysctl_register(void);
1501 extern void fuse_sysctl_unregister(void);
1502 #else
1503 #define fuse_sysctl_register()          (0)
1504 #define fuse_sysctl_unregister()        do { } while (0)
1505 #endif /* CONFIG_SYSCTL */
1506
1507 #endif /* _FS_FUSE_I_H */